LH (List Header)

The LH or list header element is used to provide a title for a list.
User agents can use this in place of the full list when a mechanism is
provided to fold and unfold nested lists.

Permitted Attributes for the LH Element

ID

An SGML identifier used as the target for hypertext
links or for naming particular elements in associated style sheets.
Identifiers are NAME tokens and must be unique within the scope of the
current document.

LANG

This is one of the ISO standard language abbreviations,
e.g. "en.uk" for the variation of English spoken in the United Kingdom.
It can be used by parsers to select language specific choices for
quotation marks, ligatures and hypenation rules etc. The language
attribute is composed from the two letter language code from ISO 639,
optionally followed by a period and a two letter country code from ISO
3166.

CLASS

This a space separated list of SGML NAME tokens and is
used to subclass tag names. By convention, the class names are
interpreted hierarchically, with the most general class on the left
and the most specific on the right, where classes are separated by a
period. The CLASS attribute is most commonly used to attach a
different style to some element, but it is recommended that where
practical class names should be picked on the basis of the element's
semantics, as this will permit other uses, such as restricting search
through documents by matching on element class names. The conventions
for choosing class names are outside the scope of this specification.